Display of current and past actions threw text - actionscript-3

Question

So iv set up a set of text to display the last actions you'v done within my game. Iv managed to get it to add the text below the current text, but how would i move all of the previous text upwards so each time it adds a new text it will place it in the same spot and only move the previous text, then delete the oldest text after a certain amount has been displayed
This is the game
http://www.fastswf.com/F7ei81E
this is the code im currently using
protected function createEventText()
{
chatScreen = new Sprite();
chatScreen.x = 280;
chatScreen.y = 520;
addChild(chatScreen);
addText("The world has spawned!");
}
public function addText(t:String)
{
eventArray.push(t);
for (var i:int = eventArray.length - 1; i < eventArray.length; i++)
{
et = new EventTextMC();
et.txt.text = String(eventArray[i]);
et.y = i * 20;
chatScreen.addChild(et);
}
}

Answer 1

What I suggest is that you keep a finite number of EventTextMC instances on your chatScreen. Then, when you add the text, you can "push" the text from the top field to the bottom field.
private var _historyLength:int = 5; // number of text fields to generate
private var _textFields:Array = []; // array to keep track of textfields
// create the finite number of fields (based on historyLength)
private function initLog():void
{
// adding 5 (historyLength) text fields to the chatScreen
for(var i:int = 0; i < historyLength;i++)
{
var et:EventTextMC = new EventTextMC();
et.y = i * 20;
textFields.push(et);
chatScreen.addChild(et);
}
}
public function addText(t:String)
{
eventArray.push(t); // this array isn't actually being used in this example
// starting with the last text field, copy the previous field's text
// this will create a "pushing down" effect
// CLARIFICATION:
// The text from the second to last field will be placed into the last field.
// The text from the third to last field will be placed into
// the second to last field.
// This will continue until the text from the first field will be placed
// in the second field, freeing up the first field for the new text.
for(var i:int = historyLength-1; i > 0; i--)
{
textFields[i].txt.text = textFields[i-1].txt.text;
}
// add the new text to the first (top-most) textfield
textFields[0].txt.text = t;
}
While I'm not actually using the eventArray in this example, you could easily use it later on to "scroll" through the logs.